The present invention relates to the utilization of high concentration sulphur dioxide gases for energy production, particularly for the production of superheated steam.
Sulphur dioxide released from fossil fuel combustion, metal smelting and other industrial activities is a world-wide air pollution problem. It is known that SO.sub.x can destroy agricultural products, damage man-made structures, imperil human health, and cause acid rain that kills aquarian life on a large scale. A growing body of evidence proves that sulphur dioxide is responsible for substantial adverse effects on public welfare and these effects can be accumulative.
In order to correct these damaging effects of SO.sub.x, the control of sulphur oxides (sulphur dioxide and sulphur trioxide) at their sources is necessary. In the past, I have developed a sulphur dioxide removal and waste product utilization process and it is described briefly as follows: gas emissions from fuel-burning furnaces, metal smelters, ore roasters, or other industrial operations are treated to separate solid particles and to oxidize the sulphur dioxide (SO.sub.2) contained therein into sulphur trioxide (SO.sub.3). The SO.sub.3 is reacted with lime (CaO) to form a calcium sulphate (CaSO.sub.4) coating. The particles are then subjected to sudden quenching, resulting in the product of this process, "Linfan". Linfan is a solid product consisting of a core of lime surrounded by a shell of anhydrous calcium sulphate which has a plurality of cracks. Linfan can be used as a plastering material, for the reclamation of fly ash, and as a high-strength construction material. It can also be used advantageously as an efficient chemical for water and waste-water treatment.
The present invention is designed to expand the aforementioned process to include steam or energy production.
Chemical Reactions and Energy Production Potential of the Process:
First, SO.sub.2 in gases is converted to sulfur trioxide in a catalytic converter according to the formula: EQU SO.sub.2 +1/2O.sub.2 .fwdarw.SO.sub.3 ; .DELTA.H=-23.5 K-cal/mole
The gas rich in SO.sub.3 is then reacted with lime to form a CaSO.sub.4 coating on the lime particles: EQU SO.sub.3 +CaO.fwdarw.CaSO.sub.4 ; .DELTA.H=-92.6 K-cal/mole
In the presence of water vapor in the high temperature lime reactor, the following reactions also take place: ##EQU1##
The total heat generated from the process is 116.1 K-cal/mole which can be used for energy development.
The gas emissions high in sulphur dioxide concentrations can be used advantageously for energy production. Copper, zinc, nickel, lead smelting off-gases, gases from pyrites and other sulphite roasting, which normally have high SO.sub.2 concentrations, are ideal for Linfan and steam production by my invention.
Liquid sulphur dioxide and elemental sulphur dioxide can also be used for energy production. When elemental sulphur is used, sulphur is oxidized to sulphur dioxide in a sulphur burner and additional heat is released by the following reaction: EQU S+O.sub.2 .fwdarw.SO.sub.2 ; .DELTA.H=-70.9 K-cal/mole
This heat can be used in the steam generation system.